1. Field of the Invention
The invention relates to a light emitting device, more particularly to a current-regulated light emitting device for vehicle use.
2. Description of the Related Art
Generally, a vehicle uses its battery to provide electric power for vehicle lights. Since battery voltage cannot be maintained at a constant level, battery power must undergo voltage stabilization and current rectification before it is supplied to the vehicle lights.
Referring to FIG. 1, a conventional voltage-stabilized light emitting device for vehicle use is shown to be adapted for electrical connection to an electric power source 61 of a vehicle, and includes a rectifier 62 adapted for electrical connection to the electric power source 61, a surge suppressor 63, a light emitting unit 64, and a voltage regulating unit 65 interconnecting the light emitting unit 64 and the rectifier 62. The light emitting unit 64 includes a plurality of light emitting components (D) and a plurality of current limiting resistors (R1). The light emitting components (D) are connected in series-pairs, and all of the series-pairs of the light emitting components (D) are then connected in parallel. The voltage regulating unit 65 includes a voltage stabilizing integrated circuit (IC), two resistors (R2), and a capacitor (C). The voltage regulating unit 65 serves to stabilize a drive voltage from the electric power source 61 before supplying the same to the light emitting unit 64.
When the electric power source 61 is unstable such that the drive voltage therefrom fluctuates, the voltage regulating unit 65 will operate to adjust the drive voltage to an appropriate value and to supply a stable current for the light emitting unit 64. In view of the need for continuous operation of the voltage regulating unit 65, the operating temperature thereof will increase, and prolonged operation at high temperatures affects operating stability and service life of the voltage regulating unit 65.